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Topic: Graphene formation  (Read 3957 times)

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Offline BigWilly

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Graphene formation
« on: February 13, 2014, 12:24:57 PM »
Hello all,
I am not a chemist so forgive me if im not communicating in proper chemist language.

Graphene may be better discussed in other places but i figured you organic chemists should know alot about carbon.

If i had a bunch of carbon atoms that i could spray onto a surface would they form bonds with each other? I assume they would. Would they naturally form in a sp2 bonded pattern?

Is it possible to isolate pure carbon? And disperse it with an inert gas?

Offline Arkcon

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Re: Graphene formation
« Reply #1 on: February 13, 2014, 01:19:31 PM »
Pretty much yes to all of those.  And graphene sheets have been formed as you describe, but I don't have a reference handy.  The bonds in graphene and graphite are akin to the bonds in benzene, so pi-bonds instead.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline BigWilly

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Re: Graphene formation
« Reply #2 on: February 13, 2014, 01:26:22 PM »
What is the best way to isolate pure carbon? Which method requires the least energy?

I guess dispersing carbon, with an inert gas, onto a substance is basically what CVD is ya?

Offline Enthalpy

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Re: Graphene formation
« Reply #3 on: February 13, 2014, 02:12:13 PM »
The vapour pressure of carbon is tiny, so would CVD or other methods transport carbon vapour? The usual trick is rather to transport one or two compounds, gaseous or easily evaporated, that react on the target surface to produce the desired coating.

A carbon compound looks like a better way to obtain pure carbon by decomposition. Graphite for instance has not nearly the purity expected from thin films and semiconductors.

Even for silica SiO2, regular purity is obtained from natural quartz crystals chosen by lack of colour (you won't take diamond?) and fused, while high purity reacts silane SiH4 and O2.

Offline BigWilly

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Re: Graphene formation
« Reply #4 on: February 13, 2014, 02:43:10 PM »
If the vapour pressure of carbon is tiny then no, CVD methods wouldn't transport carbon vapour well.

Is there a way to increase the vapour pressure of carbon?

Are there one or two compounds that will react on a surface to create graphene? I don't see this working overly well?

Would pyrolysis of graphite oxide result in graphene formation?

Offline silverz89

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Re: Graphene formation
« Reply #5 on: June 13, 2014, 07:20:24 PM »
Since the time of this post, there have been some more developments made in the "spraying" process for the formation of larger sheets of graphene from graphene flakes. It was reported late May that a Chicago (USA) and Korea joint academic team is utilizing a type of supersonic "de Laval" spray nozzle similar to those used in rocket engines. As opposed to some kind of CVD process, the high energy that the nozzle provides to the spray stream helps prevent surface deformation of the graphene as it is deposited on the substrate. I am not sure what kind of suspension the team is using (Water, water+surfactant?) or what method was initially used to create the graphene (current methods include reduction of graphene oxide, ball milling of graphite, sonication of graphite, etc), but the project is being hailed as the next step leading towards production larger macro-scale graphene structures and composites. this is big news, as current graphene "flake" sizes cannot be utilized for certain kinds of projects that exploit the unique properties of this material. i believe the team has also asserted that the new process has expanded the possibilities of deposition substrates that can achieve successful graphene formation. For more basic information on this development, you can look up "graphene supersonic spray gun" in Google or follow Link to wired.co.uk article below: http://www.wired.co.uk/news/archive/2014-05/30/graphene-spray

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